Local Delamination Buckling of a Laminated Beam due to Three-Point Bending

Abstract

Asymmetric three-point bending of a layered beam containing an interior interface crack is analyzed on the basis of the classical beam theory. Axial compressive and tensile forces are induced by bending in the parts of the beam above and below the delamination, and they are determined by modeling the cracked part as two lapped beams jointed together at the corners of both beams. When the magnitude of the applied load is small, the beam deflects, retaining the mutual contact of whole crack faces, but as the applied load reaches a critical value, local delamination buckling of the compressed part occurs. The relation between the magnitude of the applied load and the deflection at the point of load application is found to be nearly bilinear. The validity of this prediction is confirmed by experiments. It is also shown that once the delamination buckling occurs, the energy release rate generally becomes larger as compared with the case of a perfect contact of delaminated surfaces.